Unable to communicate, Pistorius says he felt trapped and invisible to the world around him.

Imagine for a moment that you're awake, but unable to speak, move or otherwise interact with the world around you. Even worse, you've been declared "a vegetable," with doctors convinced you're in a comatose state with no hope of regaining consciousness.

This was the hell that Martin Pistorius "awoke" to when he was 16 years old. Four years earlier, his otherwise normal and healthy life was rocked by a sudden, mysterious illness that started robbing him of strength, movement and eventually speech. One day, he shut down altogether — with doctors declaring him in a "vegetative state," the victim of what they believed was a degenerative disease caused by cryptococcal meningitis and tuberculosis of the brain. His parents were told to prepare for the worst.

As Pistorius explains in his memoir "Ghost Boy," he slowly started regaining his senses at age 16, eventually becoming fully aware at 19 but unable to escape his physical prison.

“My mind was trapped inside a useless body, my arms and legs weren’t mine to control and my voice was mute,” he writes. “I couldn’t make a sign or sounds to let anyone know I’d become aware again. I was invisible – the ghost boy.”

For the next several years, Pistorius motivated himself to try and physically make contact with the outside world; all the while enduring painful comments from loved ones who believed he was not there.

“I hope you die,” he remembers his mother saying in a moment of frustration.

“Every time she looked at me, she could see only a cruel parody of the once-healthy child she had loved so much.”

Pistorius recalls that to pass the time, he would solve puzzles — such was what time of day it was by watching how the shadows moved across a room. Other times, he would let his mind simply wander. "I would literally live in my imagination, sometimes to such an extent that I became oblivious to my surroundings," he told NPR.

At the age of 25, one of Pistorius's caregivers noticed that he would react to certain questions and statements. That moment of recognition, he remembers, was one for the ages.

“Happiness surged through me. I was Muhammad Ali, John McEnroe, Fred Trueman. Crowds roared their approval as I took a lap of honour,” he writes.

Today, Pistorius is happily married to a woman named Joanna and works as a web designer. Through intense physical therapy, he has regained some control of his head and arms and communicates using a voice synthesizer.

“It was she (Joanna) who has taught me to understand the true meaning of the Bible passage we were having read at the service: ‘There are three things that will endure — faith, hope and love — and the greatest of these is love’,” he said.